<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>07_DOM操作2</title>
</head>
<body>
<input type="text" id="i1" value="kk">
<input type="text" id="i2">
<button onclick="f()">按钮1</button>
<hr>
<h4>我是标题:<span id = "ss"></span></h4>
<button onclick="f2()">按钮2</button>
<script>
    function f2(){
        let spanE1 = document.querySelector('span');
        //let spanE2 = document.querySelector('#ss');
        //let spanE3 = document.getElementById('ss');
        console.log(spanE1,spanE2,spanE3);
        spanE1.innerHTML = '哈哈哈';

    }
    function f(){
        console.log(i1.value,typeof i1.value);
        let a = parseFloat(i1.value);
        console.log(a,typeof a);
    }
</script>
</body>
</html>